The invention relates to improvements in apparatus for making knots in flexible elements, particularly in so-called withdrawal strings, pull strings or drawstrings of catamenial tampons. More particularly, the invention relates to improvements in apparatus for making knots at a high frequency such as is required in connection with the production of tampons, tea bags and other mass-produced articles which are provided with strings or analogous flexible elements for convenience of manipulation. The invention will be described primarily with reference to the making and manipulation of catamenial tampons with the understanding, however that the apparatus can be used with equal or similar advantage for the making of knots in flexible elements which can be secured to a wide variety of commodities including tea bags as well as laces and many others.
It is well known to provide a catamenial tampon with a drawstring which facilitates extraction of the tampon and its disposal. It is also known to provide the drawstrings of tampons with knots so as to render it possible to more firmly engage the drawstring preparatory to and during extraction. Reference may be had, for example, to U.S. Pat. Nos. 4,543,098 (Wolfe et al.) and 3,762,413 (Hanke). A drawback of presently known methods of and apparatus for making such knots is that they are too slow and/or too unreliable. For example, the apparatus for making knots in the drawstrings of successive tampons can constitute a bottleneck in a production line which is designed to turn out hundreds of tampons per minute. Reference may be had to commonly owned U.S. Pat. No. 4,302,174 which discloses an automatic tampon making machine